Jon Michael Hill (left) and Michael McKean are terrific in Tracy Letts' "Superior Donuts," at the Music Box.Robert J. Saferstein

AFTER “Superior Donuts,” Tracy Letts’ follow-up to “August: Osage County,” premiered in Chicago last year, the play was deemed entertaining but minor.

Either this Steppenwolf production has been drastically reworked on its way to New York, or we live in a cynical world where a show as tender and honest, as beautifully written, acted and directed as this one can be blithely dismissed.

True, “Superior Donuts” is a chamber piece compared to “August” and its operatic scale. But smaller is by no means lesser.

The title of the piece is also the name of an old coffee shop in a rough Chicago neighborhood where gentrification’s beginning to take hold. The place is realistically rendered as a bare-bones emporium of sagging vinyl and rickety tables; the menu board advertises “CHOC lATE wiTh Sp INKL” and the clock stopped around 8:30.

And it does feel as if things have ground to a halt at Superior Donuts, where owner Arthur Przybyszewski (Michael McKean) is an aging hippie sporting a floppy gray ponytail.

Arthur is barely holding on to a few regulars — cops Randy (Kate Buddeke) and James (James Vincent Meredith), homeless Lady Boyle (Jane Alderman) — but he still refuses to sell the store to Max (Yasen Peyankov), an entrepreneurial Russian immigrant.

“Time change everything, and donut has been left behind,” Max warns Arthur in stilted English.

Of course, stasis isn’t very dramatic, so Letts introduces a quick-thinking African-American detonator named Franco Wicks (Jon Michael Hill). He talks his way into a job at the shop, but his real passion is the notebooks and legal pads holding his Great American Novel, “America Will Be.”

But Letts didn’t set out to write a Great American Play titled “America Used To Be.” Despite a couple of jokes about Starbucks — the lesser ones in a constantly funny stream — “Superior Donuts” isn’t an ode to how great things used to be. Instead, the characters both stay true to themselves and realize they need to evolve.

There’s a thin line between sentiment and sentimentality, but Letts always stays on the right side. He also gets a deluxe production from director Tina Landau (whose work keeps getting better and better) and a cast in a state of grace. The self-

effacing Arthur could easily have been a sad sack, but McKean imbues him with wounded dignity and a bone-dry humor, while Hill transcends the part of a smart, ambitious young man cornered by circumstances.

If all this makes “Superior Donuts” old-fashioned, so be it. The show is a timely reminder of the heady pleasure ace actors and ace storytelling can bring.